Pythagoras of Samos in Ancient Greece, lived between about 570 and 495 BC.

Pythagoras is best known as a great mathematician, but he also thought about the meaning of life. Some of his ideas became an important part of what the Greeks believed, and this has carried down through the ages to modern times.

The mathematical theorem (rule) that Pythagoras is famous for is all about triangles where one angle is a right angle. It says that the square of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the other two sides. This is used every day by engineers around the world in designing buildings.